1. Field of the Invention
The present invention relates to a color splitter and combiner system configured to modulate a light flux emitted from a light source using a reflection type image display element (liquid crystal panel) and to display an image, and a projection display apparatus having the color splitter and combiner system.
2. Description of the Related Art
As a projection display apparatus configured to project and display a color image on a predetermined surface, a known projection display apparatus reflects and transmits two color light fluxes using one polarization beam splitter, and leads each color light flux to a corresponding reflection type liquid crystal display element (liquid crystal panel).
In many cases, an incident angle of the light incident upon the polarization splitting surface of the polarization beam splitter is not constant but has latitude. Hence, the incident light is not perfectly split into the transmission light and the reflection light on the polarization splitting surface, and the light to be originally transmitted is reflected or the light to be reflected is transmitted. This light will be referred to as unnecessary light hereinafter. Then, the unnecessary light interferes with the reflected image light that is incident upon and modulated by the corresponding reflection type liquid crystal display element, via the polarization beam splitter, and an interference pattern is projected on the screen. A projection display apparatus configured to reduce the interference pattern on the screen is known. U.S. Patent Application, Publication No. (“US”) 2005/0243279 corresponding to Japanese Patent Laid-Open No. (“JP”) 2006-047968, and JP 2006-343692.
The projection display apparatus disclosed in US 2005/0243279 reduces the interference pattern on the screen by making large an axial chromatic aberration of the projection lens itself. However, the flare in the single color band is likely to occur due to this axial chromatic aberration.
The projection display apparatus disclosed in JP 2006-047968 reduces the interference pattern on the screen using a chromatic aberration plate (plane parallel plate) that is provided with an axial chromatic aberration. At this time, the spherical aberration occurs due to the chromatic aberration plate. Even for a plate glass (plane parallel plate) that has generally no power as a lens, a spherical aberration actually occurs according to its thickness. Thus, the resolving performance tends to be lower on an optical path into which the plate glass is inserted than on an optical path into which no plate glass is inserted.
When the projection display apparatus disclosed in JP 2006-343692 reduces the interference pattern on the screen using the axial chromatic aberration lens, the image quality of the projection image tends to deteriorate due to the other influence on the image quality performance, such as a chromatic difference of magnification and a telecentricity of the projection lens.